The invention relates to a support for a sound pickup in a record player, having a tangential scanning mechanism for the pickup.
In order to reduce scanning errors, record players are increasingly being provided with a tangential scanning guide for the sound pickup. In general, these structures are pickup arms having conventional dimensions as used for the radial tonearm scanning of records and which by means of controls are guided over the surface of the record along a record radius in a straight line, and not along an arc.
It is known to use such arrangements in tangential scanning systems, and with a very short tonearm, or pickup arm, for the phono cartridge, or sound pickup element. By this a number of advantages are obtained. However, problems occur in connection with the mechanical support for such pickup arms, partly due to the small dimensions, which with the very limited forces which are available may lead to imprecise guidance and stoppages. Extremely high demands are made on such pickup arms because, when scanning the sound grooves with such a limited stylus force, they must also supply the input for the control of the parallel feed mechanism, whereby they must exert only a negligible tracking pressure on the sides of the grooves. As far as possible, any friction must be avoided or reduced to a minimum, this applying to all movement directions in which a sound pickup element can move.
In connection with the mentioned short pickup arms, minimum frictional losses are obtained by bearing them at a single point, so that the pivot position of the arm in the horizontal plane is defined. To permit a vertical or approximately vertical movement of the scanning sound element, the arm must be pivotable about the point or jewel thrust bearing in a vertical plane given by the point of support and the tip of the scanning needle, or stylus. The pickup arm must not tilt sideways by moving in the direction of the vertical plane which is at right angles to this first plane. It is therefore common to provide a guide in a slot which prevents such a tilting movement. A further necessary degree of freedom of the arm is the rotation about a vertical axis passing through the jewel thrust bearing, which at the same time must not impede the pivotal movement about the point of support.